1. Field of the Invention
The invention relates to a drug solution infusion catheter, which is indwelled continuously or temporarily in a blood vessel such as an artery or a vein, for infusing drug solution such as anticancer drug.
2. Description of the Related Art
Recent years, when administering drug solution such as anticancer drug into a body, infusion of drug solution into a cancer-ridden internal organ is now being performed by inserting a catheter into a blood vessel percutaneously and placing a distal end of the catheter at an entrance of an artery, which continue to the internal organ in question, instead of using an injection syringe or drip infusion.
The catheter is inserted into the blood vessel by a well-known Seldinger technique. In other words, normally, an introduction needle formed of metal is inserted into the blood vessel percutaneously, and then a guide wire is inserted into the blood vessel through the introduction needle to make it reach the intended position. Subsequently, the catheter is inserted along the outer periphery of the guide wire to make it reach the intended position, and then the guide wire is pulled out whereby the indwelling operation of the catheter is completed. By infusing the drug solution into the catheter in this state, the drug solution is infused into the affected  area such as an internal organ. However, when a normal catheter is used, there arises a problem that blood may flow backward into the catheter due to the blood pressure.
JP-A-Sho.61-187872 discloses a catheter for administering medicament for a long term. The catheter has a one-way valve at the distal end thereof. The one-way valve is a duckbill valve. The duckbill valve provided at the distal end of the catheter includes a pair of flat bills overlapping with each other. The valve is closed in a normal state. When drug solution is infused, the valve is opened so that the drug solution flows in, whereby backflow of blood is prevented.
JP-U-Hei.4-27946 discloses a catheter with a check valve having a check valve, which allows a guide wire to pass through, at the distal end thereof. The check valve has substantially U-shape in cross section, is mounted so that the distal end is recessed when viewed form the distal end of the catheter, and is formed with a guide wire trough-hole on the bottom (valve base) thereof.